<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Title</title>
    <style>
      div {
        position: relative;
        width: 300px;
        height: 30px;
        border: 1px solid black;
      }
      div::after {
        content: "";
        position: absolute;
        top: 7px;
        right: 5px;
        width: 15px;
        height: 15px;
        border-top: 1px solid black;
        border-right: 1px solid black;
        transform: rotate(45deg);
      }
    </style>
  </head>
  <body>
    <div></div>
  </body>
</html>
